Born in the city of Bursa, Yusuf Tazim was the son of an Assassin and his wife, a pastry cook named Nalan. However, Yusuf was raised only by his mother, with the fate of his father unknown and unaware of his Assassin legacy.[1]

In 1475, as Yusuf was eight years old, the two fled Bursa in the middle of the night and went to Constantinople where they settled. There, Nalan worked for the vendor Bekir bin Salih, cooking pastries in the city's Baazar, while the young Yusuf was their delivery boy. As his mother struggled to make a decent living for the two of them, Yusuf used his agility to become a skilled pickpocket.[1]

One day, after Yusuf stole the heavy purse of a woman wearing rich clothes, an older boy followed him and attacked him in a side street. After a quick brawl during which he broke his adversary's nose, Yusuf was bested by the heavier and older boy. After telling Yusuf his name, Davud bin Hassan revealed that the money Yusuf had just stolen was everything Selime possessed after she fled her abusive husband with her children. After a shameful Yusuf accepted to give back the purse, the thirteen years old offered to train Yusuf so he could steal from the right people and defend the smallfolks of the Baazar with him.[1]

In April 1480, Nalan decided that it was time to give Yusuf some answers about his father after witnessing Yusuf and his friends' activities. She gave her son his father's hidden blade that was returned to her by the Brotherhood after her husband's death and revealed to Yusuf that his father too fought against those seeking to dominate others and intended his son to do so when the right time come.[1]

Two years later, Yusuf and Davud decided to break into the rich house of the Baazar's new owner, to steal as much as they could so they could help the merchants of the Baazar after their rents had been quadrupled, forcing many to leave. However, as the pair were discreetly looting the upper stairs of the house the owner came back home with a guest, trapping the two friends into the house. As the foreign merchant went upstair looking for alcohol to celebrate his increased wealth, Davud prompted Yusuf, the quickest of the two and the only one having a hook blade, to flee with their loot while he stayed behind to stall the merchant. As the door opened Davud jumped on the man but eventually the merchant sliced his throat as a distraught Yusuf disappeared into the night thanks to his father's weapon.[1]
While still not understanding what the merchant meant when he spoke of Templars and Assassins with his guest, Yusuf promised himself to watch for any individual wearing the mysterious red cross that he saw on the man's ring.[1]

Sometime around 1484, at the age of seventeen, Yusuf had become well known in the city as a vigilante and petty thief, which later caught the attention of Vizier and Assassin Ishak Pasha. Taken in by the man's charisma, Yusuf joined the Order just before he turned twenty.[2]

In 1502, Yusuf allied with a contingent of Venetian Assassins in Greece to bring an end to the Ottoman-Venetian war. Their efforts led to a halt in the battle, and a brief era of peace on their borders by 1503.[2]

The Ottoman Assassins enjoyed this moment of peace until 1509, when the Templars banded together under the crest of the ancient Byzantine Empire. Yusuf led the Assassins in the struggle, and his efforts eventually allowed him to be appointed the leader of his guild by 1511.[2]

In 1511, the Ottoman guild heard of Ezio Auditore's encounter with the Templars occupying the ancient Assassin fortress of Masyaf, and Yusuf himself went to meet the Mentor at the Golden Horn.[2]

While he showed Ezio around the city, he explained the current conflict between the Assassins and Templars in Constantinople, as well as that between the Ottomans and Byzantines. He also spoke briefly to him of the Assassins' more dire situation when they had been under the Byzantine Emperor, where they had been hunted down and killed on sight.[2]

Upon acquainting Ezio with the local Assassin guild in the Galata District, Yusuf introduced him to the Hookblade, a common tool of the Ottoman Assassins, which Yusuf claimed to have grown up using. After a demonstration of its features, the two climbed Galata Tower and viewed the city from above, before both performing a Leap of Faith to the street.[2]

"When the Templars take control of a district, they flaunt their presence, hanging banners, extorting the merchants. It's a constant battle to keep them at bay, and they rub our noses in every victory."

As they went to return to the guild, Yusuf and Ezio were met by one of the Ottoman Assassins, who claimed that two of their dens were under attack. Knowing he could not be in two places at once, Yusuf sent Ezio to protect the Galata den, while he traveled to the Grand Bazaar.[2]

Yusuf instructing the Ottoman Assassins

Though the Galata den was saved, Yusuf arrived too late, and the Bazaar became overrun by Templars. Ezio caught up with Yusuf in time to help him fend off several guards, and the two set off to retake the district.[2]

Upon reclaiming the den and verifying that it had not been damaged, Yusuf taught Ezio how to craft bombs, and further recommended that he find Piri Reis should he wish to learn more. At this point, Ezio also showed Yusuf the journal of Niccolò Polo, and told him of the Masyaf Keys. Though Yusuf did not know anything about the keys or the journal, he suggested that Ezio ask Piri for the directions to Niccolò and Maffeo Polo's old trading post as well.[2]

Some time afterward, Yusuf traveled to visit the Assassin allies of Constantinople; the Mercenaries, Thieves, and Romanies. However, as they were each located in different districts, Ezio offered his help in coordinating with the Romanies, which Yusuf gratefully accepted.[2]

Later in 1511, Yusuf and his Assassins discovered a planned attempt on Prince Suleiman's life, soon after he had returned from a pilgrimage. In order to protect him, they prepared to infiltrate the Prince's cultural exhibition at Topkapı Palace dressed as Italianentertainers.[2]

Ezio met with them as they discussed their plan atop the Hippodrome, and offered his help. However, Yusuf insisted that this was an Ottoman affair, and that he need not be involved.[2]

As Ezio explained that he wanted to learn more about the Masyaf Key that had been found under Topkapı, Yusuf reminded him that their mission was to protect Suleiman, not question him. However, Yusuf finally consented to Ezio's request to trust him, and so the Ottoman Assassins and the two departed to secure disguises.[2]

Yusuf pointing out the last remaining Byzantine

After knocking out and stealing the clothing of several minstrels, they managed to enter the party. As Ezio distracted the crowd and identified the concealed Byzantines with his gift, Yusuf and his men silently eliminated the targets and hid the bodies.[2]

However, the Byzantines eventually realized the danger, and killed one of the palace guards, triggering the alarm. As the Janissaries quickly told Suleiman to escape the area, the Templars desperately tried an open attempt on Suleiman's life. Yusuf broke his cover and killed several of the enemies with his blade, with Ezio intercepting the last hidden Templar, and killing him with the snapped off neck of his lute.[2]

As Ezio thought of a means of entering the well-guarded area, the two witnessed a couple of Janissaries terrorizing a nearby merchant and stealing his goods. Yusuf remarked on this oppression, and so Ezio concluded that using nearby heralds to provoke a riot would give enough cover for him to enter.[2]

However, Yusuf frowned upon this idea, saying that Ezio would manipulate the people for his own purposes. Seeing the necessity though, he merely insisted that Ezio at least protect the rioters from the attacking guards during the distraction. Upon doing so and successfully entering the port, Ezio soon discovered Manuel Palaiologos speaking with Shahkulu and Tarik, and overheard that the weapons would be bound for an unknown Templar base.[2]

In 1512, when Ezio decided to set sail for the Templar province of Cappadocia to pursue Manuel, Yusuf came to inform him that the Great Chain had been raised to block any ships from leaving. He then gave the Mentor a powerful explosive to destroy the structure, and aided him in attacking the ships that were stationed to intercept his escape.[2]

Before departing, Ezio requested Yusuf to protect his love interest, Sofia Sartor, from harm. Yusuf agreed, and he and the other Assassins guarded Sofia's residence at the former Polo trading post.[2]

Sofia's shop was soon raided by Byzantine Templars, who had secretly been working for Prince Ahmet. Yusuf faced off against the Templars inside the store and managed to eliminate many of them, but was eventually dealt a fatal blow to the back, and Sofia was taken captive by the remaining attackers.[2]

Ezio giving Yusuf his final rites

Upon Ezio's return from Cappadocia, he discovered Yusuf's body on a bench in Sofia's shop, with the dagger still pierced into him. He removed the blade and closed Yusuf's eyes, offering him his final rites and saying quietly that he had earned his rest.[2]

Enraged by both Yusuf's death and the endangerment of Sofia's life, Ezio led a large-scale assault on Ahmet's forces in the Arsenal. Though the Assassins managed to kill many of the soldiers, Ezio was forced to allow Ahmet to escape, as he still held Sofia hostage.[2]

Soon after Yusuf had been buried in a small cemetery near Galata Tower, Ezio spoke with the Ottoman Assassins who had gathered in his memory and appointed one of them as the new leader of the guild.[2]

At some point during his life, Yusuf Tazim fathered at least one child. By 2016, one of his descendants, Emir, was kidnapped by the Templars, who hoped to discover more about the interactions of Tazim with the legendary Ezio Auditore da Firenze while exploring Emir's DNA.[1]

Yusuf was a light-hearted and cheerful man, whom Ezio once described as an affable fighter. Even when engaged in battle or facing several enemies, he would often joke about the situation.[2]

Nevertheless, Yusuf was a skilled warrior and a respected leader, showing open attachment to his fellow Assassins and receiving their obedience in return. When Yusuf was murdered by Byzantines on the orders of Prince Ahmet, the Ottoman Assassins were enraged and deeply saddened. Though fighting for the Order's interests, he also acknowledged Constantinople as a whole; putting importance in the protection of their Prince, regardless of whether or not he aided the Assassins.[2]

Yusuf jokingly referred to himself as "Yusuf Tazim da Istanbul" during his first time meeting Ezio, when told that "da Firenze" indicated the city where Ezio was born. However, Yusuf's database entry claims that he was born in Bursa.

Yusuf and Suleiman were the names of two central characters in Vladimir Bartol's Alamut, on which Assassin's Creed is partially based. They were the two who performed "leaps of faith" and died for the sake of the paradise promised to them by their Master.

In the novelization, it was claimed that Yusuf was fifteen years younger than Ezio.

Yusuf is a Turkish and Arabic variant of the Hebrew name יוֹסֵף (Yosef), meaning "the Lord increases". Tazim is an Arabic name that means "to venerate, to show respect, to revere".